Air inlets for buildings used in agriculture, such as swine confinement buildings, are designed to bring fresh air into the building and provide the desired amount of air for the animals. Currently known inlets are available in fixed sizes so a building owner has to purchase an oversized inlet in order to assure the proper amount of air needed will be supplied. There is therefore a need for an improved inlet that will make it easier for a purchaser to determine the number and type of air inlets for a particular building.